A New Trigonometric Shear Deformation Theory for Bending Analysis of Functionally Graded Plates Resting on Elastic Foundations

Mohammed Ameur,Abdelouahed Tounsi,Ismail Mechab,El Abbes Adda Bedia 대한토목학회 2011 KSCE JOURNAL OF CIVIL ENGINEERING Vol.15 No.8

A new trigonometric shear deformation plate theory involving only four unknown functions, as against five functions in case of other shear deformation theories, is developed for flexural analysis of Functionally Graded Material (FGM) plates resting on an elastic foundation. The theory presented is variationally consistent, has strong similarity with classical plate theory in many aspects,does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. In the analysis, the two-parameter Pasternak and Winkler foundations are considered. Material properties of the plate are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of the volume fractions of the constituents. Governing equations are derived from the principle of virtual displacements. The accuracy of the present theory is demonstrated by comparing the results with solutions derived from other higher-order models found in the literature. It can be concluded that the proposed theory is accurate and simple in solving the static bending behavior of functionally graded plates.

Hydrodynamic study involving a maxblend impeller with yield stress fluids

Houari Ameur,Mohamed Bouzit,Mustapha Helmaoui 대한기계학회 2012 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.26 No.5

"In the present study, the hydrodynamic characteristics of the Maxblend impeller have been investigated. A commercial CFD package (CFX 12.0) was used to solve the 3D hydrodynamics and to characterize the flow patterns at every point. A shear thinning fluid with yield stress was modeled in the laminar regime and transition regime. The study focused on the effect of fluid rheology, agitator speed,impeller clearance from the tank bottom and blade size on the fluid flow and power consumption. Predictions have been compared with literature data and a satisfactory agreement has been found."

Effect of tartrazine on digestive enzymatic activities: in vivo and in vitro studies

Fatma Zohra Ameur,Nabila Mehedi,Cristina Soler Rivas,Antonio Gonzalez,Omar Kheroua,Djamel Saidi 한국독성학회 2020 Toxicological Research Vol.36 No.2

Tartrazine (E102) is a synthetic food coloring, which belongs to the class of mono azo dyes and is known to cause numerous health problems. The current research aimed to evaluate the effect of this food dye on the enzymatic activity of amylase, lipase and proteases after a subchronic ingestion in Swiss mice. Additionally, an in vitro digestion model was used to highlight the relationship between the probable toxicity of tartrazine and the nature of the food ingested. The results show that there were no adverse effects of tartrazine on the body weight gain, and on amylase or lipase activities. However, in the high dose of tartrazine (0.05%) group, a significant decrease in trypsin and chymotrypsin enzymatic activities were observed. Regarding the in vitro digestion model, our findings show that there were no changes in the trypsin and chymotrypsin enzymatic activities either using 7.5 or 75 mg of tartrazine mixed with rice, butter or milk. We conclude that excessive consumption of tartrazine appears to alter the enzymatic activity of proteases in vivo which may have deleterious consequences on digestion. Even thought the dose close to the acceptable daily intake does not affect those activities, a strict control of tartrazine dose in high-consumption foods especially among children is an indispensable task.

Numerical study of bonded composite patch repair in damaged laminate composites

Azzeddine, Nacira,Benkheira, Ameur,Fekih, Sidi Mohamed,Belhouari, Mohamed Techno-Press 2020 Advances in aircraft and spacecraft science Vol.7 No.2

The present study deals with the repair of composite structures by bonding composite patches. The composite structure is a carbon/epoxy laminate with stacking sequence [45/-45/0/90]S. The damaged zone is simulated by a central crack and repaired by bonding symmetrical composite patches. The repair is carried out using composite patches laminated from the same elemental folds as those of the cracked specimen. Three-dimensional finite element method is used to determine the energy release rate along the front of repaired crack. The effects of the repair technique used single or double patch, the stacking sequence of the cracked composite patch and the adhesive properties were highlighted on the variations of the fracture energy in mode I and mixed mode I + II loading.

CNN Auto-Encoder Network Using Dilated Inception for Image Steganography

Ismail Kich,El Bachir Ameur,Youssef Taouil 한국지능시스템학회 2021 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.21 No.4

Numerous studies have used convolutional neural networks (CNNs) in the field of information concealment as well as steganalysis, achieving promising results in terms of capacity and invisibility. In this study, we propose a CNN-based steganographic model to hide a color image within another color image. The proposed model consists of two sub-networks: the hiding network is used by the sender to conceal the secret image; and the reveal network is used by the recipient to extract the secret image from the stego image. The architecture of the concealment sub-network is inspired by the U-Net auto-encoder and benefits from the advantages of the dilated convolution. The reveal sub-network is inspired by the auto-encoder architecture. To ensure the integrity of the hidden secret image, the model is trained end to end: rather than training separately, the two sub-networks are trained simultaneously a pair of networks. The loss function is elaborated in such a way that it favors the quality of the stego image over the secret image as the stego image is the one that comes under steganalysis attacks. To validate the proposed model, we carried out several tests on a range of challenging publicly available image datasets such as ImageNet, Labeled Faces in the Wild (LFW), and PASCAL-VOC12. Our results show that the proposed method can dissimulate an image into another one with the same size, reaching an embedding capacity of 24 bit per pixel without generating visual or structural artefacts on the host image. In addition, the proposed model is generic, that is, it does not depend on the image’s size or the database source.

Influence of an initial imperfection on hygro-thermo-mechanical behaviors of FG plates laid on elastic foundation

Ismahene Belkorissat,Mohammed Ameur 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.5

The behavior of functionally graded plates with initial geometrical imperfection laid on elastic Winkler-Pasternak foundation is presented in this paper. During the manufacturing process of FG material, imperfections in the form of material and porosity may arise leading to the modification of the mechanical properties of parts manufactured from these materials. As a result, it is required to consider the hygro-thermo-mechanical behavior of FG plates having porosities in this study. Imperfect FG plates are considered to have even and uneven porosity distributions through their cross-sections. The equilibrium equations of a porous functionally graded plate are generated via the HSD-theory and the virtual work principle. The influence of porosity and material distribution parameters on the hygro-thermo-mechanical responses of the FG plate is exposed. Examples are also presented to demonstrate the impact of diversifying gradients, volume fraction of porosity, aspect ratios on the hygro-thermal and bending of the FG plates.

CNN Auto-Encoder Network Using Dilated Inception for Image Steganography

Ismail Kich,El Bachir Ameur,Youssef Taouil 한국지능시스템학회 2021 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.21 No.4

Numerous studies have used convolutional neural networks (CNNs) in the field of information concealment as well as steganalysis, achieving promising results in terms of capacity and invisibility. In this study, we propose a CNN-based steganographic model to hide a color image within another color image. The proposed model consists of two sub-networks: the hiding network is used by the sender to conceal the secret image; and the reveal network is used by the recipient to extract the secret image from the stego image. The architecture of the concealment sub-network is inspired by the U-Net auto-encoder and benefits from the advantages of the dilated convolution. The reveal sub-network is inspired by the auto-encoder architecture. To ensure the integrity of the hidden secret image, the model is trained end to end: rather than training separately, the two sub-networks are trained simultaneously a pair of networks. The loss function is elaborated in such a way that it favors the quality of the stego image over the secret image as the stego image is the one that comes under steganalysis attacks. To validate the proposed model, we carried out several tests on a range of challenging publicly available image datasets such as ImageNet, Labeled Faces in the Wild (LFW), and PASCAL-VOC12. Our results show that the proposed method can dissimulate an image into another one with the same size, reaching an embedding capacity of 24 bit per pixel without generating visual or structural artefacts on the host image. In addition, the proposed model is generic, that is, it does not depend on the image’s size or the database source.

Mechanical and hygrothermal behaviour of functionally graded plates using a hyperbolic shear deformation theory

Imene Laoufi,Mohammed Ameur,Mohamed Zidi,El Abbes Adda Bedia,Abdelmoumen Anis Bousahla 국제구조공학회 2016 Steel and Composite Structures, An International J Vol.20 No.4

Using the hyperbolic shear deformation plate model and including plate-foundation interaction (Winkler and Pasternak model), an analytical method in order to determine the deflection and stress distributions in simply supported rectangular functionally graded plates (FGP) subjected to a sinusoidal load, a temperature and moisture fields. The present theory exactly satisfies stress boundary conditions on the top and the bottom of the plate. No transversal shear correction factors are needed because a correct representation of the transversal shearing strain is given. Materials properties of the plate (elastic, thermal and moisture expansion coefficients) are assumed to be graded in the thickness direction according to a simple power-law distribution in terms of the volume fractions of the constituents. Numerical examples are presented and discussed for verifying the accuracy of the present theory in predicting the bending response of FGM plates under sinusoidal load and a temperature field as well as moisture concentration. The effects of material properties, temperature, moisture, plate aspect ratio, side-to-thickness ratio, ratio of elastic coefficients (ceramic-metal) and three distributions for both temperature and moisture on deflections and stresses are investigated.

Bearing Fault Diagnosis of a PWM Inverter Fed-Induction Motor Using an Improved Short Time Fourier Transform

Mohammed-El-Amine Khodja,Ameur Fethi Aimer,Ahmed Hamida Boudinar,Noureddine Benouzza,Azeddine Bendiabdellah 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.3

Induction motor diagnosis using the Power Spectral Density (PSD) estimation based on the Fourier Transform calculation has been widely used as an analysis method for its simplicity and low computation time. However, the use of PSD is not recommended for processing non stationary signals (case of variable speed applications) and therefore the analysis with PSD is not reliable. To overcome this handicap, the Short Time Fourier Transform (STFT) is proposed in this paper; giving additional information on changes of the frequencies over time for stator current signal analysis. Furthermore, the use of a new approach called Maxima’s Location Algorithm is also proposed. This later will be associated with the STFT analysis to show only those harmonics with useful information on existing faults. This approach will be used in the diagnosis of bearing faults of a PWM inverter-fed induction motor operating at variable speed. Several experimental results in the transient state are carried out fi rstly to validate the results and secondly to illustrate the merits and eff ectiveness of the combined STFT/ MLA proposed approach.

Diagnosis and discernment between eccentricity and demagnetization faults in PMSM drives

Koura, Mohamed Boudiaf,Boudinar, Ahmed Hamida,Aimer, Ameur Fethi,Bendiabdellah, Azzedine,Gherabi, Zakaria The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.3

This paper proposes a new approach that allows the diagnosis and the ability of discernment between the frequency signatures of eccentricity faults and those of demagnetization in a permanent magnet synchronous motor (PMSM). This approach is based on the application of a very selective band-pass filter in the stator current. A judicious calculation of the parameters of this filter makes it possible to extract only the frequency signatures of searched faults. The use of the relevant information on the magnitude and phase angle of the signatures, obtained by filtering, makes it possible to distinguish between both of the studied faults. The simple monitoring of the plotting in terms of polar coordinates of the combined information (magnitude/phase angle) of the signature's characteristic of these two faults allows for this discernment. Experimental results show the effectiveness of the proposed approach when it comes to the diagnosis reliability of demagnetization and the eccentricity faults in a PMSM.